An electrode welding method includes a laser irradiation apparatus preparation step of preparing a laser irradiation apparatus including a laser oscillator that emits a laser beam with a wavelength having absorbability with respect to a semiconductor chip and a spatial light modulator that adjusts the energy distribution of the laser beam emitted by the laser oscillator, an electrode positioning step of positioning, corresponding to electrodes of a wiring substrate, bump electrodes of a device, and an electrode welding step of irradiating the back surface of the semiconductor chip with the laser beam and welding the bump electrodes to the electrodes of the wiring substrate.